Equipment for migratory fish breeding

ABSTRACT

Problems to be solved by the present invention are: (i) to make it possible for bred fishes, such as tuna, to swim fully and safely without danger of collision to the wall; (ii) to make it possible for fry to safely survive without being eaten by young and grown fishes; (iii) to largely reduce energy consumption needed for water purification; and (iv) to largely reduce labor needed for cleaning and regenerating filter means. These problems are solved by the invention of equipment for migratory fish breeding, in which a breeding tank formed in a circle and a purified water tank formed in a shape lacking a part of a circle (an “occulted circle”) are included, both tanks closely set together like a pair of eye-glasses. The breeding tank is provided with water lanes for separating infant (fry), young, and grown fishes from each other, each given a circular water current. In the purified water tank, there is placed water filtering means and purified (filtered) water is stored there. Both tanks are held substantially at the same water level, as the tanks are mutually connected by a water duct to supply raw water to the filtering means from the breeding tank, and water injection means for injecting water into the breeding tank from the purified water tank.

FIELD OF INVENTION

The present invention relates to on shore tanks for migratory fishbreeding.

BACKGROUND OF INVENTION

The inventor-applicant of the present application owns the Japan PatentNo. 3837709 (registered Aug. 11, 2006) on an invention of on shore tanksfor migratory fish breeding. Various idea and knowledge obtained throughexecution of the patented invention have enabled the applicant topresent here a new patent application on the improvements.

Generally, water in the breeding tank, including the above patented one,needs to be pumped to clarifying tank (or inversely) to remove residualfoods or faeces floating in the water, which require a large electricpower consumption and piping. Further, there is a problem of laboriouscleaning and regenerating operations for maintaining filter means.Today, the energy costs for transferring water is becoming one ofserious managerial factors.

Patent document 1 listed below gives one of solutions against theproblems raised above, in which a clarifying tank provided with a filterlayer and a breeding tank are concentrically arranged together with anairlift system, to save electric power for transferring water and toeliminate piping between tanks. However, the invention in the documentdiffers from the applicant's in that the former deals withnon-migratory, still water fishes such as flatfishes, stone fishes ortakifugus, in which the lane arrangement with a circular water flow inthe breeding tank, that is useful in case of migratory fish breeding, isnot employed.

Patent document 1: JP-A-2002-223665

PROBLEMS TO BE SOLVED BY INVENTION

Problems to be solved by the present invention are those two taken overfrom the above-mentioned patented invention: (i) to make it possible forbred fishes, such as tuna, to swim fully and safely without danger ofcollision to the wall; (ii) to make it possible for fry to safelysurvive without being eaten by young and grown fishes; and new twoproblems to be solved at the same time: (iii) to largely reduce energyconsumption needed for water purification; and (iv) to largely reducelabor needed for cleaning and regenerating filter means.

MEASURES FOR SOLVING PROBLEMS

The above problems can be solved by the invention of equipment formigratory fish breeding, in which a breeding tank formed in a circle anda purified water tank formed in a shape lacking a part of a circle(“occulted circle” in this specification) are included, both tanksclosely arranged like a pair of eye-glasses. The breeding tank isprovided with water lanes for separating infant (fry), young, and grownfishes from each other, each given a circular water current. In thepurified water tank, there is placed water filtering means and purified(filtered) water is stored there. Both tanks are held substantially atthe same water level, as the tanks are mutually connected by a waterduct to supply raw water to the filtering means from the breeding tankutilizing a dynamic pressure of the circular water current, and waterinjection means for injecting water into the breeding tank from thepurified water tank.

ADVANTAGEOUS EFFECTS OF INVENTION

The above problems (i) and (ii) are simultaneously solved by theequipment of the present invention, in which the breeding tank isprovided with water lanes formed with net-sheets for separating fishesinto generation, and in each lane, a circular water current flows at agiven speed in the same direction. The net-sheet is a net which ispartly covered with a sheet to enhance durability for protecting fishes.

Collision accidents can be avoided by letting fishes to swim against ahigh speed water current, by making use of the fish's liking for doingso, as a relative speed against environment is lowered. At the sametime, it is possible to give the fishes necessary exercise to lessentheir frustration by allowing them to swim at the highest speed.Further, as separate lanes work for dedicated tanks for each generationof fishes, it is possible to consign fishes according to the state ofgrowth without danger of inter-generation eating.

The problem (iii) can be solved by the equipment of the presentinvention, in which the breeding tank shaped in a circle so that fishescan swim along the circular water flow, and the purified water tankshaped in an eclipse circle are closely arranged like a pair ofeye-glasses. Due to this arrangement, the distance over which water isto be transferred within the equipment is reduced to almost thethickness of the tank wall, making the piping between tankssubstantially unnecessary. In addition, as the water level differencebetween tanks is substantially zero, the energy needed to transfer thewater between tanks is minimized, and a large energy saving is attained.The above-mentioned tank arrangement makes it possible to provide thelanes in the breeding tank, and to keep a circumference ratio ofpurified water tank/breeding tank less than unity (approximately ¾ incase of the same tank diameters). On the other hand, if the purifiedwater tank is placed inside the breeding tank, it will be difficult toprovide the lanes there. Further, if the purified water tank is placedoutside the breeding tank surrounding it, the above-mentioned ratio willbe larger than unity, resulting in an increased construction cost.

The problem (iv) can be solved by the water filtering means employed inthe present invention, which require almost no labor for cleaning andregeneration operations.

DESCRIPTION OF PREFERRED EMBODIMENTS 1st Embodiment

A water duct is placed at the bottom of the breeding tank, with sidewindows on one side, against which the circular water flow hits and aportion thereof flows in. This embodiment corresponds to claim 2.

As the water duct lies across the circular water flow on the bottom ofthe breeding tank, the flow hits on one side of the rectangular duct, onwhich the side windows are made. Water is introduced into the sidewindows by the dynamic pressure of the flow. It will be appropriate tocover the windows located in the fry lane with nets, lest the fry arenot sucked down.

2nd Embodiment

Water injection means consists of a water pipe having an open endthereof on the border wall between tanks, and directing to the outeredge of the circular water flow, and a underwater screw provided in thewater pipe. This embodiment corresponds to claim 3.

The water injection means is provided with the underwater screw, theonly active component in the equipment, which produces all of the waterflows: that are circular water flow in the breeding tank; water supplyto the filtering means; and water flow to the injection means. This rolecan be fully attained with a few, small-powered underwater screws,thanks to the result of above-mentioned energy saving. The quantity ofinjected water is determined to meet a larger one of necessary waterflow for maintaining the circular flow and for purifying water.

3rd Embodiment

Filtering means consist of a hollow drum covered with a filteringmembrane and an air wheel coupled thereto, and supported horizontally byhollow shafts at both ends. This embodiment corresponds to claim 4.

The hollow drum is almost entirely dipped in the water except for itstop, and rotated together with the air wheel driven by air from an airsource. Raw water is supplied through the hollow shafts. The drum can berotated with small quantity of air as its rotation speed is moderate.Because the drum is provided with a sufficiently large membrane area,and water is filtered while flowing gently from inside to outside of thedrum, the dynamic pressure of the circular water current exerted on thewater duct is sufficient to give the pressure difference betweenmembrane necessary for filtration, and therefore, the both tanks can beat substantially the same water levels.

4th Embodiment

The filtering means is provided with plural water spray nozzles abovethe hollow drum, and the membrane is continuously reverse-washed by thenozzles. This embodiment corresponds to claim 5.

As the filtered substance is held lightly on inside of the membrane, itcan be easily reverse-washed with small quantity of washing water.Reverse-washing is carried out automatically and continuously throughoutthe operation, labor needed for cleaning and regeneration of thefiltering means is substantially zero.

EXAMPLES 1st Example

An example with respect to the invention of claim 1 will be explained inthe following with reference to the attached drawings. FIG. 1(A) is aconceptual plan view showing the equipment for migratory fish breeding,and FIG. 1(B) is a conceptual sectional view of the equipment in theA-A′ arrows direction (hereinafter “view of A-A′ arrows) shown in FIG.1(A). Purified water zone, raw water zone and oyster-shell zone areshown by respective patterns in FIG. 1 (A).

FIG. 2(A) is a view of B-B′ arrows in FIG. 1(B) in which the water duct,filtering means and water jet hole on the tank border wall are shown.FIG. 2(B) is a view of C-C′ arrows in FIG. 1(A) in which the waterinjection means consisting of the under water screw, water pipe and thewater jet hole are shown, and FIG. 2(C) is a view of D-D′ arrows in FIG.1(A) in which the buffer plates with oyster-shell layer in the purifiedwater tank are shown.

The breeding tank 1 is a circular water tank of approximately 30 metersin diameter and 11 meters high, and the purified water tank 3 is oneshaped in the occulted circle, to which the breeding tank 1 is puttogether as closely as a pair of eye-glasses, having the border wall 2in-between.

The inside of the breeding tank 1 is divided into water lanes 11, 12,and 13 for grown fish, young fish and infant fish (fry), respectively,to separate them from each other, by net-sheets 16 which only water canpass through. In the lanes, circular water currents 14 are let flow inthe same direction. Nets in the net-sheet are meshed having a size whichfishes can not pass through and placed separately in upper and lowerpositions of the net-sheet where fish density is low. A sheets is placedin the middle position of the net-sheet, and provided with strength andelasticity that can not be broken when the fishes rush at it at theirhighest speed.

The water duct 15 is laid on the bottom of the breeding tank 1 along itsradius connecting the centers of the both tanks, and introduces rawwater of the breeding tank 1 to the water filtering means 5. The waterduct is a rectangular trough placed on the bottom plate of the breedingtank 1 laid upside down and provided with side windows against which thecircular water current strikes. It can be easily removed and cleaned.

There is a tower built inside the purified water tank 3, consisting of araw water pool 31, a filter pool 32 and a purified water pool 33. Thewater filtering means 5 is placed in the filter pool 32, with its almostentire body immersed in the water. The raw water flows in the water duct15, passes through the tank border wall 2, and ascends in the raw waterpool 31 to the water filtering means.

Purified water after filtration flows out from the filter pool 32 to thepurified water pool 33 and further to the purified water tank 3, wherethe purified water is held at the same water level as that of thebreeding tank 1. A portion of the purified water is constantlydischarged to the outside and fresh water of the same quantity is addedto avoid accumulation of bacteria. The purified water flows slowly in awide water channel of the purified water tank 3, and makes its way inthe oyster shell layer while being changed its flow directions up anddown by the buffer plates 34 and increasing clearness, to adjacent ofthe water injection means 4. There, the purified water is spouted fromthe injection hole 43 and joins the circular water current 14.

Now, the breeding tank is needed to be a circle because in which thecircular water current 14 is let flow to make fishes to swim. However,as this does not apply to the purified water tank 3, it can take anyform such as a tetragon. Though, a circle gives a minimum circumferencefor a given surrounded area. If the purified water tank 3 is built in aform including a circle even if partly, flows within the tank becomesmooth resulting in savings in energy consumption and constructionmaterial. Further, if the diameters of the both tanks are the same,there arises merits in that concrete frames for construction of tankscan be utilized in common, and a good aerial appearance of the tanks isgiven.

As the result of unification of the both tanks into a single equipment,a sharp decrease in energy consumption required for transferring waterbetween the tanks has been realized. Required power for transferringwater of 6,000 liters per minute is:

-   -   750 W×3 units=2,250 W in conventional pump system, and    -   90 W×2 units=180 W in the present example.        Namely, the required power for transferring water of the same        quantity has decreased to 1/10. This is the result of decrease        in transferring distance and water head difference.

2nd Example

This example relates to the inventions of claims 4 and 5.

FIG. 3(A) shows a partially broken plan view of a hollow drum and airwheel included in a rotating drum type water filter which constitutesthe filtering means 5. FIG. 3 (B) explains the air wheel and an airsource.

The filtering means 5 is the rotating drum type water filter, whichconsists of the hollow drum 51 over which a filtering membrane 52 isstretched, and the air wheel 54 connected with the hollow drum 51,supported horizontally by rotational axes 53 at both ends.

The hollow drum 51 is immersed in the purified water up to near the topand rotated by the air wheel 54 driven by air supplied from the attachedair source 6. The raw water is supplied through the rotational axes 53and filtered while flowing from inside to outside of the hollow drum 51.

Above the hollow drum 51, there is installed water shower nozzles 7,with which the filtering membrane 52 on the hollow drum 51 iscontinuously reverse-washed. Exhaust water from reverse-washing isdrained to the outside through a drain pallet and drain pipe 8.

BRIEF DESCRIPTION OF DRAWING

FIG. 1(A): A conceptual plan view showing the equipment for migratoryfish breeding.

FIG. 1(B): A conceptual sectional view of the equipment in the A-A′arrows direction shown in FIG. 1(A).

FIG. 2 (A): A view of B-B′ arrows in FIG. 1(B) in which the water duct,filtering means and water jet hole on the tank border wall are shown.

FIG. 2 (B): A view of C-C′ arrows in FIG. 1(A) in which the waterinjection means consisting of the under water screw, water pipe and thewater jet hole are shown.

FIG. 2 (C): A view of D-D′ arrows in FIG. 1(A) in which the bufferplates with oyster-shell layer in the purified water tank are shown.

FIG. 3 (A): A view showing a partially broken plan view of a hollow drumand air wheel included in a rotating drum type water filter whichconstitutes the filtering means 5.

FIG. 3(B): Explains the air wheel and an air source.

REFERENCE SIGNS

1 breeding tank, 2 border wall, 3 purified water tank, 4 water injectionmeans, 5 water filtering means, 6 air source, 7 water shower nozzle, 8drain pallet and drain pipe, 11 water lane for grown fish, 12 water lanefor young fish, 13 water lane for infant fish (fry), 14 circular watercurrent, 15 water duct, 16 net-sheet, 51 hollow drum, 52 filteringmembrane, 53 rotational axes

1. Equipment for migratory fish breeding, comprising a breeding tankformed in a circle, and a purified water tank formed in a shape lackinga part of a circle (an “occulted circle”), both tanks being closely puttogether like a pair of eye-glasses, wherein inside of the breeding tankis separated into water lanes for infant (fry), young, and grown fishes,respectively, for separating them from each other, each lane given acircular water current flowing in the same direction; wherein waterfiltering means is placed in the purified water tank and purified(filtered) water is stored there; and wherein both tanks are held atsubstantially the same water level, as the both tanks are mutuallyconnected by a water duct to supply raw water to the filtering meansfrom the breeding tank utilizing a dynamic pressure of the circularwater current, and water injection means for injecting water into thebreeding tank from the purified water tank.
 2. Equipment according toclaim 1, wherein the water duct is laid along the radius of the bottomof the breeding tank, provided with side windows at which the circularwater current strikes and a portion thereof flows in.
 3. Equipmentaccording to claim 2, wherein the water injection means consists ofwater pipes directed to the outermost tangential line of the circularwater current, whose injection holes open on an tank border wall, and aunderwater screw installed in each water pipe.
 4. Equipment according toclaim 3, wherein the water filtering means is a rotating drum type waterfilter, which consists of a hollow drum over which a filtering membraneis stretched, and an air wheel connected with the hollow drum, supportedhorizontally by rotational axes at both ends.
 5. Equipment according toclaim 4, wherein the water filtering means is provided with water showernozzles above the hollow drum, the filtering membrane beingautomatically and continuously reverse-washed by the water showernozzles.